Bushman's Hole, on the edge of the Kalahari Desert in South Africa, is one of the strangest places on Earth. It's a prehistoric crater on an otherwise endless track of desert, and for an elite but extreme fraternity of explorers, what happened there is the stuff of myth and legend.
The terrible beauty of the place can't be seen from the air, or even the ground. But if you trace the walls down, you reach a tiny pool covered in algae. Keep going, through a narrow shaft running for another 150 feet, and finally it all opens into a vast freshwater cavern tall enough to hold the Eiffel Tower, and deep enough -- nearly 1,000 feet -- to mesmerize the most experienced, technical cave divers in the world.
Don Shirley is one of only a handful of divers who has "gone deep" at Bushman's Hole.
"It's hypnotic," said Shirley. "When you get permission to dive in a cave, as it were, the cave, it greets you, and you just want to go and explore."
Verna Van Schaik holds the women's dive record there, and said that a good dive propels you to go even deeper.
"That's the lure, that's the danger," she said. "You kind of are able to logic yourself into the fact that the risks probably aren't so real."
The environment in Bushman's Hole is so alien that deep divers compare it to space walking:
"Imagine floating," said Shirley. "So you've got no pull by gravity whatsoever… you're moving around in this cave and you can float up to a ceiling you can float around corners. And if you couple that with silence, then there's absolutely zero noise. That's a magic experience … It is a different world."
Bushman's Hole is the kind of world a young man with a thirst for thrills might love. Theo Dreyer still remembers the day, 10 years ago, when his son Deon was invited by the South African Cave Diving Association to join them as a support diver at Bushman's Hole. Deon Dryer only had two years of diving experience, but it promised to be the thrill of a lifetime.
"They wanted to go deep," said Theo Dreyer. "So [Deon] got invited along to do backup for the guys… He said 'Dad, this is an honor being asked to do this.'"
Exactly what happened on that dive, 10 years ago, is unknown. The dive team reported that while coming back up they looked down and saw Deon Dryer's cave light fading, sinking back into the abyss.
Theo Dreyer said the rest of the group tried a rescue, "but it was futile, he'd gone down too far."
There's a local legend that a man-eating serpent lives at the bottom of Bushman's Hole, but what likely killed Deon Dreyer was something more prosaic, and poisonous.
When a cave diver breathes too heavily at extreme depths -- as an inexperienced diver like Deon Dryer might -- carbon dioxide can build up in the lungs, resulting in a blackout. Deon Dryer never came back from Bushman's Hole.
"The average person, when they pass along, gets buried in a tomb and there's somewhere you can go where there's a living memory and you can go share some thoughts," said Theo Dryer. "We didn't have that. I mean, there was no body. There was nothing."
The memory of Deon Dreyer faded, but Bushman's Hole remained a bright jewel, luring some of the best cave divers in the world. Among them was Dave Shaw. Ten years after Deon Dryer's death, in October 2004, Shaw undertook a kind of dive never attempted at Bushman's Hole.
Shirley explained that most world records for diving are what he calls "soap on a rope," -- where divers descend quickly and come right back up again.
But Shaw dove nearly 900 feet, and he attempted a few minutes of unprecedented exploration at the bottom.
"Nobody swims at depth," said Van Schaik. "It's just not done. They'll say you are stupid to swim at depth. But this was proper exploration it was brand new."
When Shaw reached 800 feet, the air mixture in his air tanks began to produce narcosis --what divers call "rapture of the deep."
"It's the effect of the nitrogen in the air that you breathe," said Van Schaik. "And it basically is equivalent to being drunk. So you lose your ability to mentally process and you lose your coordination."
At 876 feet, Shaw reached the cave floor, and did something no deep cave diver has ever done before: he moved away from his main line, cautiously exploring a previously unseen world, where he discovered something he did not expect. It was the body of Deon Dreyer.
"When I discovered Deon, he was lying on his back," said Shaw. "Hand flat, with his arms floating, due to the buoyancy of his wet suit that he was wearing. He still had his mask in place, but the body, part of the body that I could see, had no flesh on it."
Unable to pry the body from the silt, Shaw marked its location with a feeder line, and began a lonely, slow journey back to the top, carrying with him the strange news of his discovery.
After 10 hours underwater, Shaw emerged from Bushman's Hole. He was hardly out of his wet suit when he passed news of the discovery to Deon Dryer's parents, Theo and Marie.
Theo Dryer said that at that moment he was shocked. "It takes a while to sink in. … it's unreal."
Shaw then made an amazing proposition: He offered to go back down and try to bring back Deon Dryer's body.
"I'd come to accept that Deon would never be recovered," Theo Dryer said. "So you get comfortable with the idea. Now all of a sudden, they offer… to recover Deon…[and] there's doubt. Should I leave him there? He's happy there. Or should we recover? But then, yes, we went for the recovery."
Van Schaik said that Shaw and Shirley were the perfect team to attempt the rescue. "They created the perfect team. I think Dave had the drive and the ambition, and Don had the know-how and expertise and his own ambition. Um, but together they were able to… you know, to conquer this."
Shaw and Shirley were attempting the deepest underwater body recovery in history, and South African film producer Gordon Hiles thought it would be a good opportunity for a one-of-a-kind documentary film.
Hiles said that "the number of people who have dived deeper than 250 meters, that, that number is smaller than the amount of people who have actually walked on the moon."
In the weeks after the discovery of Deon Dreyer's body, events moved swiftly. Shaw and Shirley developed a complex dive plan that would require as many as nine different divers working at varying depths. The big question was how to bring the body to the surface.
"The best response I got was, there could be some soft tissue still but mainly [it will] be a skeleton," said Shirley. "And because of that, we were worried about the body falling apart literally, as it was coming up, and that's where the bag idea came from…"
Ann Shaw, Dave's wife, sewed a body bag that would be used to carry Deon Dryer's body.
Most of the equipment being readied for the dive was familiar to both Shaw and Shirley, but Shaw's helmet camera -- designed by Hiles -- was new and untried.
Two days before the final dive, the full team began assembling at Bushman's Hole, each member with a specific duty. Shaw would go the deepest and retrieve the body.
"His instruction was very simple, that you know, if something did go wrong, um, nobody was to play the hero or risk their own lives to come and fetch him," said Van Schaik.
"It cannot be any other way. It's better to have one person dead than two. It's as simple as that," said Shaw.
Those were his public instructions, but privately, Shirley and Shaw had an agreement.
"The agreement was that if Dave needed me, he would… signal with a light," said Shirley.
"It's a very solemn thing when you're actually doing a serious dive you really can't have people asking you questions or doing anything," said Shirley.
Van Schaik coordinated the dive from the surface, and since this was a body recovery, police divers temporarily tagged the site as a crime scene, and spectators begin to gather. Theo and Marie Dryer were among those who came to watch.
The dive plan called for Shaw to descend to 886 feet, place Deon Dryer's body in the body bag and bring him up to Shirley, waiting at 725 feet. From there the body would be passed through a series of divers all the way to the surface, while Shaw and Shirley began their 10-hour ascent and decompression back to the top.
It was calculated that Deon's body would reach the surface 70 minutes after the start of the dive, but the 70-minute mark came and went, with no sign of the body.
"At around 70 minutes, when the police divers didn't come up, when they're expected, I thought something had gone different. Not something had gone wrong, but something had gone different to what was planned," said Van Schaik.
Five hundred feet down, Shirley was having the same thought. "I was looking down, and I would expect to see bubbles coming back up from Dave on his ascent, but I didn't see those bubbles."
Shirley said he saw only a "small pinprick of a light" that wasn't moving.
Van Schaik suspected that Shaw was suffering deep water narcosis. "He was running in a very high narcotic depth," she said. "And it affects the way you think as well. You really have to focus hard to get your mind to solve problems."
"The agreement that Dave and I had was if he had a problem, he would signal and move the light," said Shirley. "The light wasn't moving. What I thought is that, if I could get to him, then I might be able to bring him round if he'd passed out or, or something, I could bring him back."
Shirley started to descend, but at about 800 feet, deeper than he's ever gone, he suddenly heard a loud crack. It was the sound of the controller that regulated his oxygen shattering under the immense pressure. In the time it takes for a single breath, Shirley's hope of finding his friend turned into a battle to save himself.
Without his controller, Shirley had to manually control his air supply. He had no choice now but to abandon the rescue, but he was 100 feet deeper than the original plan, which had set off a chain reaction with the support divers above him.
Peter Herbst,who was to have met Shirley at 240 feet, began to descend further, looking for either Shirley or Shaw, and carrying a diver's writing slate.
A stillness descended on the dive site, and Theo and Marie Dryer left the pool. Underwater, Herbst finally saw a lone light: it was Don Shirley. Herbst says he asked Shirley if he was OK, and Shirley motioned for the writing slate. . "I pulled the slate out," Herbst said, "and I gave him the slate, and he just wrote, 'Dave is not coming back.'"
"The whole world began to spin, literally to spin," said Shirley. "And it was like I was in another world, like in a dream."
With his controller broken, Shirley's air mixer began to produce a toxic cocktail in his body, and he began to suffer from the decompression disorder known as "the bends." Shirley faced nearly 8 hours of decompression before he could emerge from Bushman's.
"I did not know whether Don would be able to last, mentally and physically from that depth, he was too deep," said Van Schaik.
Above the hole, medical personnel readied a decompression chamber.
"You can say a lot of things about the personalities of people who get into water. You can like them, you can dislike them. But at the end of the day, the fact is Don had such a strong willpower to live… it was just not an option for him to die," said Van Schaik.
Finally, 12 hours and 23 minutes after starting his dive, the call was made to bring Shirley out.After seven hours in the decompression chamber, his condition had stabilized enough for him to be transferred to a hospital.
At Bushman's Hole, support divers and friends return to the water's edge to memorialize Dave Shaw.
"You are where you wanted to be. I'm going to miss you, mate," said Herbst.
A few divers slipped back into the water to retrieve loose lines and equipment from the failed dive, and then a police diver whispered something into Herbst's ear.
"He says, 'We saw Deon's body,'" said Herbst. "They actually saw Dave's body, with Deon hanging below him. And I just couldn't figure this out. You know, because we must have swam right past them… and we just didn't see it."
The bodies of Dave Shaw and Deon Dryer had somehow floated up from the bottom of the cave and lodged in a crevice near the surface.
"[Dave] promised to bring Deon back, and he did," said Van Schaik. "God works in mysterious ways. I think if you do deep diving for long enough, you have no choice but to believe that there is a higher power out there, because Dave bought Deon back."
Shaw also brought something else back: the helmet camera. And along with it, the answers to what really happened in the darkness of Bushman's Hole.
"Without this [camera], there would have been so much speculation as to what happened to Dave. Did he give up? Did he do something that was completely stupid?" said Shirley.
According to Shirley two critical events triggered the tragedy. First, the body was more unwieldy than expected, and second, Shaw's hand light was drifting loose at his side. Normally he would have slung the light, which was tethered to him by a power cord, over his head and rested it on his shoulder, but that was not possible because of the helmet camera on his head. As a result, the light became twisted and tangled in his lines.
As he struggled to untangle the line, Shaw was "in trouble," said Shirley.
"He's in trouble now." Shirley said. "He's caught; he can't actually get away. He's finding it difficult to, to breathe… the breathing's too shallow."
Eventually the breathing slowly faded away.
Shaw's ashes were scattered at sunset on a hill not far from where he died. Just last month, Don Shirley and Ann Shaw returned to Bushman's Hole for a chance to remember and reflect. Shirley said he doesn't have any regrets.
"Dave died, and it's a great tragedy and I really miss him. But he died doing something that he loved doing."
And Shirley said that deep divers recognize the dangers they face on each an every dive.
"I never rule out the fact that nature is there, and it will take you if you step over the bounds."